<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title></title>
    <style>
        .red {
            color: red;
        }

        .blue {
            color: blue;
        }
    </style>
</head>
<body>

<div id="app"></div>
<script src="main.js" type="module"></script>
</body>
</html>